SHARE -
If 2 then --AR- since: --A-- is known, PENCE=0, CHALK=1, CHIRP=1, so only one of R and P is correct, therefore SH are not correct in SHARP=2.
If 1 then --A-P since: --A-- is known, PENCE=0, CHALK=1, CHIRP=1, so only one of R and P is correct and R is not correct because SHARE=1